A typical control system for controlling motor vehicle safety devices is shown in DE-A-2 151 399, and includes two sensors, which are piezoelectric crystals. When mechanically stressed by the acceleration of the vehicle, the sensors generate an electrical output voltage. The output voltage is supplied through a stranded cable and processed by a control unit.
One disadvantage of this system is that because it uses only a few sensors, its operability is jeopardized should one of the sensors become inoperative. Furthermore, the attempted solution of an arbitrary number of sensors has not solved the problem, since the reliability of the safety device is not increased. An increased number of sensors merely increases the complexity of the wiring and connecting means. As viewed over the life of the vehicle, this introduces numerous sources of error.
Another safety control system for motor vehicles is shown in U.S. Pat. No. 4,381,829, which uses several acceleration detectors distributed in various locations on the vehicle. All of the acceleration sensors are connected through a multiplexer to an analog to digital converter. The analog to digital converter converts output signals of the analog sensor into digital signals. The digital signals are then supplied to a microprocessor. One disadvantage of this system is that only the output signals of each respective sensor, which are selected by the multiplexer, are available for evaluation at a given time.
It is an object of the present invention, therefore, to overcome the problems and disadvantages of known control systems for controlling motor vehicle safety devices.